ABSTRACT
A BIM model contains information relevant to planning, construction and operation. 3d geometry is one of the most important information without many BIM applications would not be possible. An important trend in the building industry is parametric modelling in order to adapt models quickly to changing constraints. Especially in tunnelling, changes in geometry are possible at any time, for example adjustments of the alignment caused by measurement inaccuracies. In case of tunnelling, the arc length of the horizontal alignment (stationing) is the most important parameter. The paper highlights requirements and describes different aspects of geometric modelling for tunnels. A focus is on geometric modelling approaches of the alignment as the basis of 3d models. Furthermore, the current status of open standards such as IFC alignment for infrastructure buildings is presented.
